It is hereby further declared to be in the public interest and highly advantageous to the agricultural economy of the state that farmers, producers and growers commercially producing the commodities referred to in this article shall be permitted by referendum to be held among the respective groups and subject to the provisions of this article to levy upon themselves an assessment on such respective commodities or upon the acreage used in the production of the same and provide for the collection of the same for the purpose of financing or contributing toward the financing of a program of research, education, advertising and other methods designed to increase the consumption of and the domestic as well as foreign markets for such agricultural products.